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jameszhjw Forum Member


Joined: 25 Jul 2013
      Posts: 1

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Posted: Thu Jul 25, 2013 2:20 pm Post subject: SAP HANA - does data storage block size impact IO so much? |
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I am doing SAP HANA performance testing.
I used the testing file size as 1GB, 5GB, 10GB and etc.
In each file size, I tested different block sizes for Log and Data - I tried 4k, 16k, 64k, 1MB, 16MB and 64MB block size.
The result is:
1. the file size (1GB, 5GB or 10GB) doesn't bring much difference.
2. The block size shows very different results: when the block size is less than 1MB, the IO performances are very poor - the Write IO is even poorer than Read IO; when the block size is more than 1MB, the IO performance improves signicifantly.
I was wondering why the block size may impact the IO so much?
And, if using block size less than 1MB, what factors can I change to improve the IO performance so that it's comparable with that of block sizes more than 1MB?
Thanks! |
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Marek Chladny Forum Advocate


Joined: 27 Nov 2003
                Posts: 19319 Location: Bratislava

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Posted: Thu Jul 25, 2013 2:24 pm Post subject: Re: SAP HANA - does data storage block size impact IO so muc |
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[Moderator Note: Moved from General Discussion to Other Products]
And welcome to B B! |
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richardcottave Principal Member


Joined: 30 Mar 2006
             Posts: 305

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Posted: Thu Jul 25, 2013 2:40 pm Post subject: Re: SAP HANA - does data storage block size impact IO so muc |
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I don't know about HANA but if it is analogous to a disk drive the block size has an impact on performance. A smaller block size requires more blocks to store a file. This in turn requires more reads and writes to the file allocation table so performance is degraded. With a disk drive you can optimize block size by calculating the average file size then make your block size as close to the average file size as possible. I have no clue if HANA works the same way though. |
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